Help? Went to Autozone and got 4 code readouts (PO171, PO174, PO1132, PO1151) on a "check engine" light and subsequent rough idle. Truck runs OK but idles rough and stalls on occasion.

I cleaned the MAF sensor, and now the truck idles up and down...different than before.

Does this sound like multiple O2 sensor failures or MAF? PVC has plenty of vacuum so I have ruled this out.

 

Those are codes for both front O2's. It's possible that they are both bad but I'd be looking more to something that affects both banks of the engine such as a vacuum leak or bad MAF. Did this only happen after you cleaned the MAF? When you cleaned the MAF did you make sure that all the hoses are connected ok to the air intake? Maybe take some Carb Medic carb cleaner spray and check for vacuum leaks too. If you spray it around the intake and the idle changes anywhere you've found a leak.

 

Thanks for the reply. I cleaned the MAF after the code check. The idle changed from intermittent drops to steady pulse with rising and falling RPM's.

I'll try the spray and the PVC elbow that I have been hearing about.

 

Thanks for your help. It turns out that the PVC elbow at the rear of the intake had a hole. I put Duct tape on it for tonight until I can get the part. Thanks again for your input on this!

 

Thanks for letting us know what you found

 

PCV elbowfor 98 expedition 5.4L...is it adviseable to replace the PCV hose assembly or just the "elbow" behind the throttle body? The dealer wants $30.87 for a new PCV assembly, but the part I need is about $3.

The explanantion given was that the part was upgraded in 2000, but this is questionable. Any advice on this?

 

I had the same problem. Replacing just the elbow soved it.